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Dynamic transcriptional and metabolic responses in yeast adapting to temperature stress.

ABSTRACT: Understanding the response processes in cellular systems to external perturbations is a central goal of large-scale molecular profiling experiments. We investigated the molecular response of yeast to increased and lowered temperatures relative to optimal reference conditions across two levels of molecular organization: the transcriptome using a whole yeast genome microarray and the metabolome applying the GC/MS technology with in-vivo stable-isotope labeling for accurate relative quantification of a total of 50 different metabolites. The molecular adaptation of yeast to increased or lowered temperatures relative control conditions at both the metabolic and transcriptional level is dominated by temperature-inverted differential regulation patterns of transcriptional and metabolite responses and the temporal response observed to be biphasic. The set of previously described general environmental stress response (ESR) genes showed particularly strong temperature-inverted response patterns. Among the metabolites measured, trehalose was detected to respond strongest to the temperature stress and with temperature-inverted up and downregulation relative to control, mid-temperature conditions. Although associated with the same principal environmental parameter, the two different temperature regimes caused very distinct molecular response patterns at both the metabolite and the transcript level. While pairwise correlations between different transcripts and between different metabolites were found generally preserved under the various conditions, substantial differences were also observed indicative of changed underlying network architectures or modified regulatory relationships. Gene and associated gene functions were identified that are differentially regulated specifically under the gradual stress induction applied here compared to abrupt stress exposure investigated in previous studies, including genes of as of yet unidentified function and genes involved in protein synthesis and energy metabolism. Reference: Strassburg K, Walther D, Takahashi H, Kanaya S, and Kopka J. Dynamic transcriptional and metabolic responses in yeast adapting to temperature stress. OMICS JIB, 2010, 14(3), in press.

ORGANISM(S): Schizosaccharomyces pombe Saccharomyces cerevisiae

PROVIDER: GSE15352 | GEO | 2010/01/01

SECONDARY ACCESSION(S): PRJNA117133

REPOSITORIES: GEO

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Project description:Understanding the response processes in cellular systems to external perturbations is a central goal of large-scale molecular profiling experiments. We investigated the molecular response of yeast to increased and lowered temperatures relative to optimal reference conditions across two levels of molecular organization: the transcriptome using a whole yeast genome microarray and the metabolome applying the GC/MS technology with in-vivo stable-isotope labeling for accurate relative quantification of a total of 50 different metabolites. The molecular adaptation of yeast to increased or lowered temperatures relative control conditions at both the metabolic and transcriptional level is dominated by temperature-inverted differential regulation patterns of transcriptional and metabolite responses and the temporal response observed to be biphasic. The set of previously described general environmental stress response (ESR) genes showed particularly strong temperature-inverted response patterns. Among the metabolites measured, trehalose was detected to respond strongest to the temperature stress and with temperature-inverted up and downregulation relative to control, mid-temperature conditions. Although associated with the same principal environmental parameter, the two different temperature regimes caused very distinct molecular response patterns at both the metabolite and the transcript level. While pairwise correlations between different transcripts and between different metabolites were found generally preserved under the various conditions, substantial differences were also observed indicative of changed underlying network architectures or modified regulatory relationships. Gene and associated gene functions were identified that are differentially regulated specifically under the gradual stress induction applied here compared to abrupt stress exposure investigated in previous studies, including genes of as of yet unidentified function and genes involved in protein synthesis and energy metabolism. Reference: Strassburg K, Walther D, Takahashi H, Kanaya S, and Kopka J. Dynamic transcriptional and metabolic responses in yeast adapting to temperature stress. OMICS JIB, 2010, 14(3), in press. Time-series with 8 time points for three different ambient temperatures. Single replicate per time point and temperature series.

Project description:Cellular responses to maladaptive environmental changes—stresses—allow for organismal adaptation to diverse and dynamic conditions. Across the tree of life, cells upregulate a highly conserved transcriptional program in response to so-called proteotoxic stresses such as heat shock. Correspondingly, in eukaryotes, these stresses induce the formation of biomolecular condensates, clusters of mRNA and protein which are referred to as stress granules under severe stress. However, major questions remain about this stress-induced response. How conserved is the condensation response relative to the transcriptional response? How does it vary across environmental niches, and to what extent does it correspond with the conserved transcriptional response? To answer these fundamental questions, we studied the growth, transcriptional, and condensation heat-induced stress responses in three fungal species adapted to thrive in different thermal environments: cryophilic S. kudriavzevii, mesophilic S. cerevisiae, and thermotolerant K. marxianus. Here we show that transcriptional heat shock responses track each species’ evolved temperature range of growth. Further, orthologous proteins—including poly(A)-binding protein, Pab1, a core marker of stress granules—form condensates in vivo at temperatures systematically tuned to the temperature at which the organisms activate the transcriptional heat shock response and slow their growth. In vitro, purified Pab1 from each species condenses autonomously at niche-specific temperatures. Homologous mutations in Pab1 cause similar shifts in relative condensation temperature across species, and crucially, mutations which suppress condensation in vitro also reduce fitness during heat stress. Our findings indicate that stress-induced protein condensation is adaptive, conserved, integrated with the growth and transcriptional responses, and tuned to features of the cellular and organismal environment to initiate at niche-specific levels.

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Project description:Diurnal temperature cycling is an intrinsic characteristic of many exposed microbial ecosystems. However, its influence on yeast physiology and transcriptome has not been studied in detail. In this study, 24-h sinoidal temperature cycles, oscillating between 12 and 30M-BM-0C, were imposed on anaerobic, glucose-limited chemostat cultures of Saccharomyces cerevisiae. After three diurnal temperature cycles (DTC), concentrations of glucose, and extracellular metabolites, as well as CO2-production rates showed regular, reproducible circadian rhytms. DTC also led to waves of transcriptional activation and repression, which involved one sixth of the yeast genome. A substantial fraction of these DTC-responsive genes appeared to primarily respond to changes in glucose concentration. Elimination of known glucose-responsive genes revealed overrepresentation of previously identified temperature-responsive genes as well as genes involved in cell cycle and de novo purine biosynthesis. Analyses of budding index and flow cytomery demonstrated that DTC led to a partial synchronization of the cell cycle of the yeast populations in the chemostat cultures, which was lost upon release from DTC. Comparison of DTC results with data from steady-state cultures showed that DTC was sufficiently slow to allow S. cerevisiae chemostat cultures to almost completely acclimatize their transcriptome and physiology at the DTC temperature maximum, and to approach acclimation at the DTC temperature minimum. The aim of this study was to investigate the impact of diurnal temperature cycles on the physiology and transcriptome of S. cerevisiae and to assess the extent to which these responses can be predicted from steady-state analyses. To this end, we used a continuous cultivation set-up, in which the yeast was grown under controlled conditions and subjected to 24-h sinoidal temperature cycles. Since the sampling volume was kept within 5% of the reactor volume during 24 h, sampling from two independent duplicate cultures for microarray analysis was spread over the fifth and sixth temperature cycle. Sample points from the fifth and sixth temperature cycle were combined, resulting in six sample points covering one temperature cycle (at temperatures of 30; 21; 14.6; 12; 21 and 27.4M-BM-0C). For the last time point, one additional analytical duplicate sample was taken. Furthermore, steady-state chemostat cultures at constant temperatures of 12M-BM-0C and 30M-BM-0C (independent duplicate cultures at both temperatures) were sampled for microarray analysis. All this resulted in a total array set of 17 arrays.

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Dynamic transcriptional and metabolic responses in yeast adapting to temperature stress.

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